Micromorphological Features of the Seed surface of Porana s.l. (Convolvulaceae) from China and Its Taxonomic Significance

Micromorphological features of seed surfaces of Porana s.l.(Convolvulaceae),inclu ding ten species and one variety,were examined under scanning electron microscope(SEM)for the first time.The result indicated that micromorphological features of seed surfaces of Porana s.l.could be divided into two types,namely the palmate venation type and the pinnate venation type,with three subtypes in the first type.To divide Porana s.l.into 4 or 5 genera is not supported by micromorphological features observed,because the rest species of Porana s.l.have similar micromorphological features except P.volubilis Burm.f..Micromorphological features of seed surfaces,pollen morphology and macromorphology were comparatively analyzed,and it was demonstrated that,although the features provided few criteria to subdivide Porana s.l.,micromorphological features of seed surfaces could be used as reliable diagnostic characters to identify species.Micromorphological features of seed surfaces do not support to raise P.racemosa Roxb.var.sericocarpa C.Y.Wu to P.truncata Kurz.In addition,due to specific micromorphological features of the type species P.volubilis Burm.f.,the relationship between it and the rest species in Porana s.l.should be studied further.